Wear-resistant vane for rotary compressor



July 17, 1962 P. H. DAVEY 3,044,687

WEAR-RESISTANT VANE F OR ROTARY COMPRESSOR Filed Feb. 17, 1959 INVENTOR.Pnue. H. DH EY FTTOR/VEYS anagram WEAR-RESESTANT VANE FUR RQTARYCGIVKPRESSOR Paul H. Davey, Davey Compressor Company, Kent, Ohio FiiedFeb. 17, 1959, Set. No. 793,879 1 Claim. (Ci. 230--152) T his inventionrelates to improvements in a wear resistant vane for rotary compressors,and more particularly to such a vane composed chiefly of metal of highheat con ducting capacity and light weight, but having a thinwearresistant layer of harder metal on those surfaces of the vanesubjected to Wear, which harder metal is substantially bonded to themain body of the vane.

One of the objects of the present invention is to provide an improvementin the radially slidable vanes of a rotary compressor or pump of a knowntype wherein a cylindrical rotor is rotatably mounted within acylindrical stator with the axes of the stator and rotor memberseccentric, there being a plurality of radially extending slots in one ofthe members, usually the rotor, opening radially outwardly, and aplurality of vanes snugly received, usually one in each of the slots,and reciprocate.- ble therein to maintain contact with the wall of theother of said members, usually the stator, so that air or other gasentering the stator at or near the point of greatest eccentricity iscarried around the rotor by the vanes and exhausted from the stator at apoint near the zone of least eccentricity.

Another object of the present invention is the provision of an improvedvane for sealing between the rotor and stator of a rotary compressor orthe like, wherein the vane is constructed chiefly from a solid body ofmetal of low density and high heat conducting capacity chosen 3 from thegroup consisting of essentially magnesium and essentially aluminum,wherein the vanes are provided with a very thin layer of a harder metalsubstantially bonded to the main body of the vane.

Other objects and advantages of this invention will be apparent from theaccompanying description and drawings and the essential features thereofwill be set forth in the appended claim.

In the drawings FIG. 1 is a transverse sectional View through a rotarycompressor embodying my invention;

FIG. 2 is a sectional view greatly enlarged taken through one of thevanes of FIG. 1;

FIG. 3 is a view similar to FIG. 2 being a cross section of a vanegreatly enlarged and showing a modification of my invention; while ing apumping action.

FIG. 4 is a fragmental sectional view through a rotary I compressorutilizing the vanes of FIG. 3.

It is the aim of the present invention to improve on the vanes commonlyencountered in rotarycompressors' today. A usual form of such vanes isto make them of laminated plastic material in an attempt to getsuflicient strength, resistance to heat and wear, and still obtainsuitable sealing between the rotor and stator. Such laminated vanes havegiven great operating difficulties resulting largely from theprogressive delamination of the vanes which operate at a relatively hightemperature in a heavy mist of oil fog, together with a high degree offriction between the vanes and the slots in which they move radiallyduring the operation of the compressor.

Another difiiculty in the use of the laminated plastic vanes mentionedin the preceding paragraph has been the deterioration of the oil used inthe lubricating oil system of the compressor. It is a known fact thatthe heat of compression in a rotary compressor of thi type is largelyaccumulated at the leading edge of each vane, which is the last portionin contact with the air as it reaches its point of greatest compression,and therefore the zone of greatest temperature. This, together with thefriction of the radially outermost edge of the vane against the statorcauses the radially outermost edge of each vane to become very hot.Since the transfer of heat through a laminated plastic vane is poor, theleading edges of these vanes are unable to dissipate the hightemperatures and, therefore, they cause a progressive delamination ofthe blades and a destructive action of the heat on the lubricating oilwhich is in contact with the heated vanes sufiiciently to raise the oilabove its polymerization point which often breaks down the oil, intogummy masses. it is therefore desirable that the heat thus naturallyconcentrated at the leading edges of the vanes or blades should beconducted away in a material of high heat conducting quality, such asaluminum and magnesium, and

spread quickly over the entire surface of the blades, from which it canbe quickly and eifectively removed by the mist of lubricating oilprovided inside the compressor.

In the following description of my invention, I shall describe first apreferred form of my invention wherein thin layers of steel are cladupon a main body of alumitruth to provide the vane for the compressor,and this will be followed by a modification in which steel is clad uponmagnesium, and then I shall describe another modification where analuminum alloy adapted to resist wear and abrasion, .is clad orotherwise deposited upon a main body of tougher aluminum.

In FIG. 1, I have shown a cross section through a rotary compressoradapted to utilize my invention. In a cylindrical stator 10, iseccentrically mounted a cylindrical rotor 11 on a shaft Elia by means ofwhich the rotor is turned by any desired motive power. A plurality ofvanes 12 reciprocate in radial slots 13 of the rotor so as to close thegap between the rotor and stator dur- Inlet to the compressor is throughthe opening 14 and the inlet passage 15 extending part way around thestator. This is at the point of greatest eccentricity. The compressedgases are discharged through the outlet 16 which is near the point ofminimum eccentricity. In the usual manner, one or more small passageways17 are provided to vent the bottom of each slot 13 so that the vanes mayreciprocate I freely in their receiving slots.

A preferred form of my invention is illustrated in FIGS. 1 and 2 whereinthe main body of the vane 12 may be of any commonly used alloy chieflyaluminum, having the necessary strength to function as a vane in therotary compressor. For instance, I have used No. 2014 aluminum which hasapproximately the following anal ysis: 4.4% copper, 0.8% silicon, 0.8%manganese, 0.4% I

magnesium and the balance aluminum. To each of the side wearing surfacesof the vane I secure, substantially by a molecular bond, a thin layer 18of steel. A preferred form uses SAE 1040 steel although I may also usesteel having quite a wide range of analysis and have used SAE-l020 andalso stainless'steel for this purpose.

The drawing of FIG. 2 is greatly exaggerated. In an actual embodimentwhere the vane was seven inches long, about 1 inches wide and inchthick, the layer 13 was approximately .019 inch thickon each side. Forthe purposes of my invention, it is not imperative that the steel layerextend clear to the edge of the vane and in an actual embodiment thedistance A from the end of the steel layer to the end of the vane isapproximately inch.

In one manner of forming the vane of FIG. 2, the heated aluminum body 12between the thin sheets of steel 18 are submitted to a terrific pressurein a 20,000

0 ton press, the purpose being to create practically a amass? at thistime is displaced by the flow of the heated aluminum under the heavypressure.

The term, molecular bonding, as used herein, refers to the bond obtainedby pressing together in a high capacity press two dissimilar metals suchas layer 18 of stainless steel and body 12 of aluminum (as seen in FIGS.1 and 2) to obtain a strong and tenacious bond. This molecular bond isobtained by the very high pressures employed, under which, as previouslyindicated, the heated aluminum flows between the stainless steel andaluminum surfaces to form the strong pressure bond.

A compressor constructed as disclosed hereinabove in FIGS. l and 2 isvery efficient. The parallel side faces of the vane where they rub theembracing slot 13 are protected against wear by the steel coating 13.This action is lubricated by the usual oil mist which is utilized in therotary compressor. At the same time, the heat which tends to collect atthe radially outermost edge of each vane is readily carried away throughthe aluminum where the heat transfer coefficient is very high. In anycase, the amount of steel present is very small. Above all, the vane isof light weight which is of great advantage in a rotary compressor.

In the modification of FIGS. 3 and 4, the cylindrical stator is shown at20 and the cylindrical rotor at 21. A plurality of vanes 22 reciprocatein radially extending slots 23. One such vane is shown in greatlyenlarged cross section in FIG. 3. Here the main body 22 of the vane iscomprised as before of aluminum and the protective layer of steel 24extends not only along the two parallel side surfaces of the vane butalso continuously around the leading edge thereof as indicated at 24a.This construction would only be resorted to if one desired to reduce theamount of wear at the radially outermost edge of the vane. The vane ofFIG. 3 is made in a similar manner to that described in connection withFIG. 2. The thin sheet 24 of steel, say, approximately 0.019 inch thick,is folded around an aluminum slug in U-form and then the heated aluminumis subjected to a very high pressure as previously described so as tocreate substantially a molecular bond between the steel and aluminum.

The structure of FIGS. 3 and 4 operates in exactly the same way as thatdescribed in connection with FIGS. 1 and 2.

As a further modification, either the structure of FIGS. 2 or 3 may bemade utilizing a block or main body 12 or 22 of magnesium in place ofthe aluminum previously described. A high strength magnesium alloy, ascommonly used today, is suitable for this purpose and the steel layers13 or 24 may be bonded to the magnesium body of the vane by the use ofheat and extremely high pressure as previously described.

The magnesium of the last described form of my invention would serve todissipate the heat through the vane from the leading edge thereof in thesame manner as occurred in connection with aluminum, and at the sametime the magnesium vane would be even lighter than the one made ofaluminum.

A further modification of my invention comprises the pressure bonding ofa relatively low strength aluminum 4. bearing alloy to a high strengthaluminum vane body so that the combination provides high strength aswell as a surface with excellent bearing characteristics against thesides of the slots 13 or 23. To this end, the main body of the vaneeither 12 or 22 is made of the No. 2014 aluminum previously described.To the side of such a vane I pressure bond two thin sheets as indicatedat 18 in FIG. 2 or a single thin sheet in U-shape form as shown at 24 inFIG. 3, such thin aluminum sheets being made of a bearing aluminumcommonly used for connecting rods and known as aluminum alloy No. 195.Such an alloy ha 4 to 5 percent copper, 1 percent iron, 1.2 percentsilicon, 0.3 percent manganese, 0.03 magnesium, 0.3 zinc, 0.2 titaniumand the balance approximately 92 percent of aluminum. In this alloythere is approximately 0.15 percent limit to the total impurities. Topressure bond the aluminum alloy No. to the No. 2014 aluminum base doesnot require quite such high pressure as the bonding of steel to aluminumor magnesium previously described. The desired condition is to havesubstantially a molecular bond between the high strength main body ofthe vane and the relatively low strength but friction resisting bearingalloy which provides the outer surface at 18 or 24.

Other modifications of my invention will appear to those skilled in theart but I believe that I have given enough illustrations of my inventionto illustrate the same as defined in the following claim.

What is claimed is:

A vane for a rotary compressor and the like, having a stator and aneccentric rotor mounted therewithin, in which the vane is adapted toreciprocate in a slot of the rotor, while maintaining contact with thestator wall, the vane having fiat parallel sides and comprising a mainbody portion of a light weight metal of the group consisting ofmagnesium, aluminum, an alloy consisting chiefly of magnesium, and analloy consisting chiefly of aluminum, and a thin surface layer portioncovering at least the major portion of the parallel sides and consistingof a metal more abrasion resistant than said main body portion, saidlayer portion molecularly bonded to said body portion by the action ofheat and high pressure in a high capacity metal press in which a strongbond is obtained by flow under the high pressure of the light metalbetween said layer and body portions.

References Cited in the file of this patent UNITED STATES PATENTS559,324 Dyer Apr. 28, 1896 1,495,526 Phillips May 27, 1924 2,216,053Staley Sept. 24, 1940 2,394,185 Jaworowski et a1 Feb. 5, 1946 2,588,342Bidwell Mar. 11, 1952 2,905,376 Davey Sept. 22, 1959 2,908,073 DulinOct. 13, 1959 FOREIGN PATENTS 308,394 Great Britain Mar. 28, 1929565,447 Great Britain Nov. 10, 1944 795,204 Great Britain May 21, 1958

